Gernandt, David S. , Leon Gomez, Calixto , Hernandez Leon, Sergio , Olson, Mark .
Ovulate cone anatomy of Pinus nelsonii.
Pinus nelsonii is a rare pinyon pine endemic to the Sierra Madre Oriental of Mexico. It is classified in the monotypic subsection Nelsoniae, making it one of only two monotypic lineages in the genus, the other being P. krempfii from Vietnam. Neither of these unusual species was taken into account when the anatomical limits between Pinus and the fossil form-genus Pityostrobus were proposed. Ovulate cones of P. nelsonii were collected in San Luis PotosÃ in August 2004. The central axis and several scales were embedded in parafin, sectioned on a rotary microtome, and examined under low magnification. The anatomy of the cone conforms to the generic concept of Pinus. In the cone axis, the pith contains sclereids; the vascular cylinder is undissected except where vasculature leads to bract-scale complexes; a growth ring is present in the xylem, as are two rings of resin canals with thin-walled epithelial cells; the cortex is composed of parenchyma cells and resin canals are also present. The cone scales are apically swollen, with a dorsally-positioned umbo. At the base of the scale, resin canals are abaxial to the vascular bundles, but at the level of the seeds the canals are abaxial, adaxial, and between the vascular bundles. Sclerenchyma is also present in the scales. Other features of the ovulate cone of P. nelsonii, and the relevance of these characters for inferring relationships in Pinus, will be presented.
Log in to add this item to your schedule
1 - Instituto de Biología, Universidad Nacional Autonoma de Mexico, Departamento de Botánica, A. p. 70-367, Mexico, D.F., 04510, Mexico
Presentation Type: Poster:Posters for BSA Sections
Location: Event Tent/Cliff Lodge
Date: Monday, July 27th, 2009
Time: 5:30 PM